Figure 5.

Subcellular distribution of MORs and GIRK channels in the dorsal horn. Electron micrographs showing MOR and GIRK subunit labeling in the dorsal horn (lamina IIo). Den, Dendritic shaft; b, axon bouton. A-D, MOR immunoparticles were found in the extrasynaptic (arrows) and perisynaptic plasma membrane (crossed arrows) of dendritic shafts establishing asymmetrical synapses with presynaptic boutons. MOR immunoreactivity was also observed in axon boutons establishing asymmetrical synapses with dendritic shafts, either along the extrasynaptic plasma membrane (arrowhead) or within active zones (double arrowheads). E, F, Postsynaptic colocalization of MORs and GIRK2 using a preembedding immunogold method. The HRP reaction product represents MOR immunoreactivity, and it filled dendritic shafts with GIRK2 immunoparticles organized along the extrasynaptic plasma membrane (arrows). G, Using a postembedding immunogold method, GIRK2 immunoparticles (10 nm) and MOR immunoparticles (20 nm) were found postsynaptically within the same asymmetrical synapse. H, Presynaptic colocalization of MORs and GIRK2 using a preembedding immunogold method. The HRP reaction product (MOR immunoreactivity) filled the axon terminal, whereas GIRK2 immunoparticles were found along the extrasynaptic plasma membrane (arrowhead). Note the postsynaptic GIRK2 immunoparticle (arrow). I, J, Postsynaptic colocalization of MORs and GIRK1 using a preembedding immunogold method. The HRP reaction product (MOR immunoreactivity) filled dendritic shafts, whereas GIRK1 immunoparticles were found along the extrasynaptic plasma membrane (arrows). Scale bars, 0.2 μm.